Cash and Cash Equivalents and Short Term Investments - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 65,244	$ 500,499	$ 476,904	$ 197,708
Term deposits	8,300	413,600
Non current term deposits with banks	229	77
Restricted Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Term deposits	$ 540	$ 600